The major users comprise 15 investigators working actively on various projects supported by NIH. The major projects for which the requested instrument will be used are concerned with the understanding of various aspects of the contractile, membrane and transport proteins. More specifically, the Principal Investigators are studying: 1) structure- function relationships in myosins; 2) thin filament regulation of muscle contraction; 3) structure- function relationships in the Ca-ATPase and the Ca2+- release channel of sarcoplasmic reticulum; 4) oxidative phosphorylation and H+ transport in mitochondria; 5) the mechanism of protein secretion and transport; 6) effect of diabetes on collagen crosslinks; 7) regulation of exogenously induced operons; 8) characterization of an antigenic determinant of a protein at the cell surface- epiglycanin. In order to study the relevant interactions within and between the protein constituents of these systems at different levels of reconstitution, chemical modification and crosslinking experiments with a variety of reagents will be carried out and the information on the primary structure of various proteins is required. For all of these projects an amino acid analyzer/ sequencer system that offers sensitivity, reliability, versatility, efficiency and automation is essential. The Applied Biosystems Model 470A Gas-Phase Sequencer along with the model 470A PTH analyzer and 900 Data System/ Controller and the Beckman Model 6300 High Performance Amino Acid Analyzer are the most suitable equipment available that will fulfill our need. The new facility will not only enhance the progress of many research projects, it will also help us to solve some problems that are otherwise beyond our reach.